This invention relates to a refrigeration cycle and, in particular, to a system for reducing or removing parasitic losses in a refrigeration system where refrigerant being cycled through the system is used to cool various related component parts of the system.
Heretofore, refrigerant used in refrigeration systems has been utilized to provide cooling to the system's compressor motor or to the oil used to lubricate the compressor motor. Recently, as disclosed in copending application Ser. No. 09/268,573 filed in the name of the present inventors and the disclosure of which is herein incorporated by reference, apparatus has been devised wherein refrigerant from a refrigeration system has been utilized to cool the variable frequency drive (VFD) used to control the compressor motor. The VFD contains power electronics in the form of insulated gate bipolar transistors that generate a relatively large amount of heat. Failure to properly cool these electronic components can result in early failure of the motor control system.
In these prior art cooling arrangements, condensed refrigerant is drawn from the system condenser and placed in heat transfer relationship with part or parts requiring cooling to remove parasitic heat losses. The refrigerant is then returned to the system evaporator and mixed with the in process refrigerant. The refrigerant used for cooling the system related components must thus be processed through the evaporator and passed through the compressor prior to being returned to the condenser thereby adversely effecting the performance of the refrigeration system. In the case where more than one system related component is being cooled, the load on the machine due to parasitic losses can be relatively high. Because the parasitic losses remain generally constant regardless of machine operating conditions, the adverse effect of parasitic losses becomes more pronounced when the machine is operating under partial load.